How to Calculate Your GPA (Weighted, Unweighted, and the Plus/Minus Scale)

If you have a transcript in front of you and a calculator in another tab, you can get your GPA in five minutes. Here is the exact method the Crunch Numbers GPA Calculator uses, from the plus/minus scale to cumulative totals.

The 4.0 scale with plus/minus grades

Before you average anything, each letter grade needs a point value. On the standard 4.0 plus/minus scale, the conversion is:

This is the table our calculator uses. If your school does not use plus/minus grades, you would use the whole-letter values only, but the method is the same.

The formula: credit hours are the weights

The GPA formula is simple:

GPA = sum of (grade points × credit hours) / total credit hours

Credit hours are the weights. That is all course-level weighting means in this calculation. A 4-credit course has four times the pull of a 1-credit course. A B+ in a 4-credit course is not just a B+ sitting next to other grades; it contributes 3.3 × 4 = 13.2 quality points.

If you enter your courses, grades, and credit hours into the GPA Calculator, it applies this formula live as you type, so you can see the average update without doing the multiplication by hand.

Worked semester example

Here is a semester converted step by step:

Add the quality points: 12.0 + 13.2 + 11.1 + 9.0 + 8.0 = 53.3. Add the credits: 3 + 4 + 3 + 3 + 2 = 15. Divide: 53.3 / 15 = 3.55 GPA.

Weighted vs unweighted GPA

At the high school level, the terms mean something different.

An unweighted GPA is the same average ignoring how hard the classes were. A regular English class and an AP English class both use the same 4.0 scale, so an A is an A.

A weighted GPA — the 5.0-scale kind some high schools report — adds a bonus for honours or AP classes. That makes an A in an AP class worth more than an A (that idea gets its own section below), and that is why two schools can report two very different numbers for the same student. Colleges often recalculate GPAs to their own scale, so always ask which number a school is quoting you before you compare yourself to an admissions average.

Cumulative GPA: why it is not the average of averages

Your cumulative GPA uses the same formula over everything you have ever taken: total quality points across all semesters, divided by total credits across all semesters. It is not the average of your semester GPAs — unless every semester happened to carry the same number of credits.

Take our worked semester (3.55 over 15 credits, 53.3 quality points) and follow it with a 3.20 semester of 12 credits (3.20 × 12 = 38.4 quality points). The cumulative is (53.3 + 38.4) / 27 = about 3.40. The lazy average, (3.55 + 3.20) / 2, gives 3.38 — close, but wrong, because it pretends the 12-credit semester pulled as hard as the 15-credit one.

Projecting next semester

The formula also runs forward. Replace the grades in the table with the grades you expect, and it tells you where you land before the semester starts. The lesson hiding in the weights: a single heavy-credit course moves the average more than two light ones combined. A B in a 4-credit course costs 4.0 quality points against an A; two 1-credit courses at the same grade cost 2.0 between them. If you are choosing where to spend study time, spend it where the credits are.

When the question flips from "what is my average" to "what do I need on the final to keep it", that is the Final Grade Calculator's job. And when a raw score needs turning into the percentage that becomes a letter grade in the first place, the Percentage Calculator handles that step.